从子Javascript访问父方法

Question

How can I access baz() from inside the bar() function in the following code?

var obj = {
    baz : function(){ alert("Hi!"); },
    foo: {
        bar: function(){ 
            baz(); 
        }
    }
}

Answer 1

JavaScript doesn't have kind of a built-in parent reference because an object can be referenced by multiple 'parents' in what we call a many-to-one relationship.

As others have said, in this simplified case, simply calling obj.baz() will work.

In a more complicated case, you would have to manually build the object and track parenthood:

// Create the root object
var rootObject = {baz: function() {console.log('rootBaz');}}

// And the basic child
var childObject = {foo: function() {console.log('childFoo');}}

// Configure the parent
childObject.parent = rootObject;

// Add our call.
childObject.baz = function() {this.parent.baz()};

// Invoke and test
childObject.baz();

Which can be slightly simplified:

var rootObject = {
  baz: function() {console.log('rootBaz');}
};

var childObject = {
  foo: function() {console.log('childFoo');},
  baz: function() {this.parent.baz()}
};

childObject.parent = rootObject;
childObject.baz();

Updated per Sujet's comment

In addition, if you need to make sure that baz has the correct value for this you can use either call or apply .

  baz: function() {this.parent.baz.call(this.parent)}

If your code doesn't require this then I would recommend a straight function call per my original answer.

Answer 2

Just use the object reference:

var obj = {
    baz : function(){ alert("Hi!"); },
    foo: {
        bar: function(){ 
            obj.baz(); 
        }
    }
}

Answer 3

You need to reference via object.property notation.

In your example you would get baz via:

obj.baz()

Some great resources for this :

• http://www.w3schools.com/js/js_objects.asp
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects